1. Field of the Invention
The invention disclosed herein relates to optimizing telemetry using a mud column as a transmission medium.
2. Description of the Related Art
Exploration and production of hydrocarbons generally requires the use of a bottom hole assembly disposed in a drill string. Different bottom hole assemblies can be used to perform several tasks in a borehole. For instance, a bottom hole assembly can be used for well logging or sample testing of a formation.
In some instances, when the bottom hole assembly performs a task, at least one result of the task needs to be transmitted uphole to the surface of the earth. Mud-pulse telemetry is a technique for transmitting data from the bottom hole assembly to the surface of the earth. Mud-pulse telemetry can also be used to transmit data or commands from the surface of the earth to the bottom hole assembly.
Mud-pulse telemetry uses at least one of pressure and flow fluctuations of mud in a column in the borehole. The characteristics of the mud column as a transmission medium for telemetry signals depend on a multitude of factors. The factors include mud type, depth in the borehole, number of pumps pumping the mud, physical condition of the pumps, and flow rate of the mud. Consequently, the factors can affect the signal to noise ratio of signal transmissions. The signal to noise ratio can limit the amount of data that can be transmitted per unit of time (i.e., limit bandwidth). Certain applications require a bandwidth greater than the bandwidth a traditional mud-pulse telemetry system can provide.
Therefore, what are needed are techniques to improve the bandwidth of mud-pulse telemetry.